In a case where a user accesses an application server (hereinafter referred to as the AP server) which provides a service by executing an application program, there is a method of proxy authentication in which a request for authentication is made on behalf of the user. In an apparatus that carries out proxy authentication, pre-authentication of a user is performed e.g. according to a combination of a user ID and a password (authentication information). Then, the user properly authenticated in the pre-authentication is authenticated by an AP server to be used by the user using authentication information registered in advance. This makes it possible to save the user the time and trouble of inputting the authentication information to each of a plurality of AP servers. Further, in an organization, such as a company, an administrator of the system manages authentication information for using AP servers, and performs the setting of proxy authentication, which makes it unnecessary for each user to take the trouble of managing authentication information for AP servers on an AP server-by-AP server basis.
The above-described function of proxy authentication includes a type in which a proxy authentication function is provided e.g. on a terminal device (terminal proxy authentication). In a case where terminal proxy authentication is introduced into an organization, such as a company, an administrator of the system is caused to distribute authentication information to terminal devices of users who are allowed to use a service provided by an AP server. However, in terminal proxy authentication, authentication information is provided to all of the terminal devices whenever the authentication information is registered, deleted, or changed. Therefore, if the number of users increases, the burden on the administrator in providing authentication information becomes too large. Further, if a browser or the like of the terminal device is caused to store authentication information, there is a risk of leakage of authentication information which might be caused by spyware or computer viruses.
To cope with such problems, it is envisaged to perform proxy authentication by centralized administrative control of authentication information in a server provided separately from terminal devices. For example, there has been proposed a technique of performing proxy authentication in an SSO (Single Sign-On) server. Further, there has been proposed a technique of performing proxy authentication in a proxy server. (See Japanese Laid-open Patent Publication No. 2010-003119 and Japanese Laid-open Patent Publication No. 2005-011098)
However, conventionally, the efficiency of processing in performing proxy authentication has been insufficient. Therefore, there is a problem that when the number of users who use proxy authentication processing becomes large, processing load on the apparatus that carries out proxy authentication becomes too large.